The mass production technology of conventional large electrically excited luminescent devices is mature. There are already signboards using electrically excited luminescent devices. Due to their characteristics of ultra-thinness and softness, the electrically excited luminescent devices have difficulty when used in commercialized signboards. Moreover, the cold-light plate usually can not be separated into several cold-light units for assembly. Therefore, the size of cold-light signboards can not be large due to limited material cost. The lead-out line terminal on the back of the cold-light plate usually exceeds outer edge of the cold-light plate, so more space is needed and the ensemble delicacy is destroyed. It is not suitable to the assembly line process. Also, accessory devices such as the converter used in the cold-light signboard usually can not be integrated with the cold-light signboard, resulting in inconvenient usage.